In Rubens's workshop practice drawings played an important role. First he made a quick sketch, usually drawn and washed in brown ink. (In some cases, however, he painted the first designs in grisaille on a panel.) Next he produced a detailed "modello" in colour (a sketch in oil), which was submitted to the client who either approved it or gave his comments on it. Once the composition existed in the shape of a definitive modello, all kinds of anatomical details were established in separate detail studies. Thus he made chalk drawing from nude male models posing for him in attitudes required by the composition. The many studies of heads played also an important role in the practice. Finally Rubens made several further studies of movement details. However, there are also drawings by his hand of architectural details, trees, animals and even farm implements.